Botanically-Derived Δ9-Tetrahydrocannabinol and Cannabidiol, and Their 1:1 Combination, Modulate Toll-like Receptor 3 and 4 Signalling in Immune Cells from People with Multiple Sclerosis.

John-Mark Fitzpatrick,William Hind,Eric J Downer,Lisa Costelloe,Becky Hackett

doi:10.3390/molecules27061763

Abstract

The innate immune response to bacterial and viral molecules involves the coordinated production of cytokines, chemokines, and type I interferons (IFNs), which is orchestrated by toll-like receptors (TLRs). TLRs, and their intracellular signalling intermediates, are closely associated with multiple sclerosis (MS) pathogenesis. Recent data from our laboratory reported that the plant-derived cannabinoids, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), regulate viral and bacterial inflammatory signalling pathways controlled by TLR3 and TLR4 in macrophages. The aim of this study was to assess the impact of THC and CBD, when delivered in isolation and in combination (1:1), on TLR3- and TLR4-dependent signalling in peripheral blood mononuclear cells (PBMCs) from people with MS (pwMS; n = 21) and healthy controls (HCs; n = 26). We employed the use of poly(I:C) and lipopolysaccharide (LPS) to induce viral TLR3 and bacterial TLR4 signalling, and PBMCs were pre-exposed to plant-derived highly purified THC (10 μM), CBD (10 μM), or a combination of both phytocannabinoids (1:1 ratio, 10:10 μM), prior to LPS/poly(I:C) exposure. TLR3 stimulation promoted the protein expression of the chemokine CXCL10 and the type I IFN-β in PBMCs from both cohorts. THC and CBD (delivered in 1:1 combination at 10 μM) attenuated TLR3-induced CXCL10 and IFN-β protein expression in PBMCs from pwMS and HCs, and this effect was not seen consistently when THC and CBD were delivered alone. In terms of LPS, TLR4 activation promoted TNF-α expression in PBMCs from both cohorts, and, interestingly, CBD when delivered alone at 10 μM, and in combination with THC (in 1:1 combination at 10 μM), exacerbated TLR4-induced TNF-α protein expression in PBMCs from pwMS and HCs. THC and CBD displayed no evidence of toxicity in primary PBMCs. No significant alteration in the relative expression of TLR3 and TLR4 mRNA, or components of the endocannabinoid system, including the cannabinoid receptor CB1 (encoded by CNR1 gene) and CB2 (encoded by CNR2 gene), and endocannabinoid metabolising enzymes, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGLL), was determined in PBMCs from pwMS versus HCs. Given their role in inflammation, TLRs are clinical targets, and data herein identify CBD and THC as TLR3 and TLR4 modulating drugs in primary immune cells in vitro. This offers insight on the cellular target(s) of phytocannabinoids in targeting inflammation in the context of MS.

Highlights

The innate immune system is a conserved system of defence that discriminates between pathogens and self via intricate cellular responses governed by toll-like receptors (TLRs), a member of the family of signalling pattern recognition receptors [1]
This study set out to determine if the phytocannabinoids THC and CBD, when delivered alone and in a 1:1 combination, target TLR3 and TLR4 signalling in primary immune cells isolated from healthy controls (HCs) and/or people with MS (pwMS)
The novel finding is that when THC and CBD are administered in combination (1:1), at a concentration of 10 μM:10 μM, the phytocannabinoids are effective inhibitors of TLR3 induction of the chemokine CXCL10 and type I IFN-β, in peripheral blood mononuclear cells (PBMCs) from both multiple sclerosis (MS) and control cohorts

Summary

Introduction

The innate immune system is a conserved system of defence that discriminates between pathogens and self via intricate cellular responses governed by toll-like receptors (TLRs), a member of the family of signalling pattern recognition receptors [1]. TLRs are expressed in immune cells and cells of the nervous system [2] where they recognise pathogen-associated molecular patterns that include viral and bacterial molecules such as double-stranded RNA and lipopolysaccharide (LPS). In terms of human studies, the expression profile of TLR3 and TLR4 is elevated in active MS brain lesions [15], and TLR4 is upregulated in CSF mononuclear cells from people with MS (pwMS) [16], with data from our laboratory demonstrating that immune cells from pwMS are hypersensitive to LPS in terms of pro-inflammatory cytokine expression [17]. Peripheral blood mononuclear cells (PBMCs) from pwMS, when compared to PBMCs from control subjects, are refractory to TLR3 stimulation, in terms of IFN-β production [18], indicating that TLR signalling may shape inflammatory responses to viral and bacterial infection at a cellular level in pwMS

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